lsfd: fill UID column with the process's uid

lsfd: fill UID column with the process's uid

The original code fills the column with the owner id of the executable
file. Because lsfd fills USER column field by decoding UID column, the
USER in lsfd meant the owner name of the executable.

On the other hand, lsof fills the USER column with the process's user
name.

To avoid users confusing, this change makes lsfd do the same lsof;
filling UID column with the process's uid.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>